A 70-foot sinkhole that killed a south-central Missouri hunter was so well hidden by foliage that some rescue workers nearly dropped into because they couldn't see it, the Pulaski County sheriff said.

Curtis Powelson, 31, died after he fell into the sinkhole Monday evening while tracking a deer near his home in Buckhorn, just outside of Waynesville, Sheriff Ron Long said. Powelson was a Marine who trained military police officers at nearby Fort Leonard Wood.

After his wife reported him missing Monday, emergency responders and neighbors searched for hours before discovering Powelson's body in the sinkhole early Tuesday. The hole was covered by foliage and was difficult to see in the dark.

"We had some deputies that were real close and didn't see it, also some firefighters that almost went off into the sinkhole," Long told KSPR-TV.

Several people rappelled into the sinkhole to retrieve Powelson's body.

"We had to do that cautiously too because this was a very new sinkhole, the sides were freshly collapsed, and just getting up to the edge you could see the dirt and ground giving away," the sheriff said.

The hole might be a part of a cave system, he said, and it heavy rains last month might have caused it to emerge. Long said he's concerned other sinkholes might open in the area, which is home to many military families and is being developed.

The hole is too large to fill and will be fenced off, he said.

"I kind of use that term loosely because I've seen sinkholes before and this was nothing like I've seen before," Long said. "It was very cylindrical."